To provide an exhaust gas purification catalyst having excellent catalyst performance in the lower layer even making the upper layer thick, adsorption efficiency of cold HC, HC purifying efficiency and NOx purifying efficiency, a manufacturing method therefor and an exhaust gas purification method.
In the exhaust gas purification catalyst, catalyst layers are laminated on a carrier in succession, and exhaust gas components purified in the n-1 layer flow into the clearance in the n layer. In the catalyst, layers containing Pd and layers containing Rh are laminated on the carrier in succession, and they have the clearance wherein the pore diameter is 0.04-10 μm, the porosity P1 and P2 are in a relation of P2>P1, and the ratio of porosity P2/P1 is 1.1-3.0. An HC adsorption catalyst layer is coated with catalyst slurry containing a clearance forming material, the clearance is formed by baking, catalyst layers are laminated thereon and the exhaust gas purification catalyst is manufactured. The catalyst adsorbs HC at 200°C or lower of the exhaust gas temperature. When the temperature of the exhaust gas rises, the catalyst desorbs and purifies HC. When the operation is repeated from a lean region to a stoichiometric region to a rich region after the temperature rise, the catalyst adsorbs NOx, and desorbs and purifies it.
ITO JUNJI
SUGA KATSUO
